Nickel(0)-catalyzed [2 + 2 + 2] cycloaddition of diynes and 3,4-pyridynes: novel synthesis of isoquinoline derivatives

摘要

A transition metal-catalyzed [2 + 2 + 2] cycloaddition between α,ω-diynes and 3,4-pyridynes has been realized for the first time, producing isoquinolines in good yields by using a nickel(0) catalyst.rnThe transition metal-catalyzed [2 + 2 + 2] cycloaddition of alkynes is a useful and highly atom-economic way to construct various aromatic rings. In recent years, arynes have been utilized as substrates in [2 + 2 + 2] cycloadditions. Pyridynes are the analogues of arynes containing a nitrogen in the ring, and can be classified into 2,3-pyridyne and 3,4-pyridyne by the position of the nitrogen in the ring (Fig. 1).